JSON schema & decode object #300

dineshkumar02 · 2020-12-30T12:42:23Z

dineshkumar02
Dec 30, 2020

Hi Team,

I am playing with the latest JSON schema extension, and it is working as per the json schema drafts.
But, I am having trouble to decode the valid JSON into the object type.

For example, consider the below situation.

I have defined one of the properties of the json schema as like below.

  "run": {
          "description": "run properties",
          "type": "object",
          "oneOf": [

            { "$ref": "#/definitions/os_properties" },
            { "$ref": "#/definitions/db_properties" },
            { "$ref": "#/definitions/api_properties" }

          ]
        },

And, defined the object to hold one of the properties as like below.

struct run_properties {
	jsoncons::optional<os_job_properties>  os_properties;
	jsoncons::optional<db_job_properties>  db_properties;
	jsoncons::optional<api_job_properties> api_properties;
};

struct job_properties {
	string				name;
	bool				enable;
	job_kind            kind;
        run_properties run;
.....
.....
.....
}

And defined the traits for the run_properties as like below.
JSONCONS_N_MEMBER_TRAITS(run_properties, 0, os_properties, db_properties, api_properties)

	string flow_props = R"(
	{
        "name": "test flow",
        "schedule": "some cron expr",
        "enable": true,
        "job": 
        {
            "name": "test event",
		    "enable" : true,
		    "kind": 	"os",
            "run": {
                "command": "test command"
            }
})";

I am passing the above JSON which is schema qualified, but, I am unable to get the "run" object property into the "os_properties" object. I am also not getting any errors, and the os_properties object don't have any value also.

And, here is the os properties object definition.

struct os_job_properties {
	string                                            command;
	jsoncons::optional<map<string, string>>            environment;
	jsoncons::optional<string>                        fail_exit_code_expression;
	jsoncons::optional<string>                        pass_exit_code_expression;
};

danielaparker · 2020-12-30T20:26:42Z

danielaparker
Dec 30, 2020
Maintainer

The types os_job_properties, db_job_properties, and api_job_properties also need traits defined. jsoncons can only decode into types that it knows about, or that have traits defined, either using the macros or explicitly. Please post a complete example, and I'll have a look.

What compiler are you using? Does it support std::variant?

1 reply

dineshkumar02 Dec 31, 2020
Author

Hi @danielaparker ,

Thank you very much for your quick responses, and please find below code which I am trying to do.

#include <jsoncons/json.hpp>
#include <jsoncons/decode_json.hpp>
#include <jsoncons/encode_json.hpp>
#include <jsoncons_ext/jsonpath/jsonpath.hpp>
#include <jsoncons_ext/jsonschema/jsonschema.hpp>
#include <jsoncons_ext/jsonpatch/jsonpatch.hpp>
#include <iostream>
#include <string>
#include <fstream>

using json = jsoncons::json;
namespace jsonschema = jsoncons::jsonschema;
namespace jsonpatch = jsoncons::jsonpatch;
using namespace std;

struct os_properties {
	string command;
};

struct db_properties {
	string query;
};

struct api_properties {
	string target;
};


struct run_properties {
	jsoncons::optional<os_properties> os_props;
	jsoncons::optional<db_properties> db_props;
	jsoncons::optional<api_properties> api_props;
};

struct job_properties {
	string name;
	run_properties run;
};

JSONCONS_N_MEMBER_TRAITS(os_properties, 1, command)
JSONCONS_N_MEMBER_TRAITS(db_properties, 1, query)
JSONCONS_N_MEMBER_TRAITS(api_properties, 1, target)
JSONCONS_N_MEMBER_TRAITS(run_properties, 0, os_props, db_props, api_props)
JSONCONS_N_MEMBER_TRAITS(job_properties, 2, name, run)

string test_schema = R"(
{
  "title": "job",
  "description": "job properties json schema",
  "definitions": {
    "os_properties": {
      "type": "object",
      "properties": {
        "command": {
          "description": "this is the OS command to run",
          "type": "string",
          "minLength": 1
        }
      },
      "required": [ "command" ],
      "additionalProperties": false
    },
    "db_properties": {
      "type": "object",
      "properties": {
        "query": {
          "description": "this is db query to run",
          "type": "string",
          "minLength": 1
        }
      },
      "required": [ "query" ],
      "additionalProperties": false
    },

    "api_properties": {
      "type": "object",
      "properties": {
        "target": {
          "description": "this is api target to run",
          "type": "string",
          "minLength": 1
        }
      },
      "required": [ "target" ],
      "additionalProperties": false
    }
  },

  "type": "object",
  "properties": {
    "name": {
      "description": "name of the flow",
      "type": "string",
      "minLength": 1
    },
    "run": {
      "description": "job run properties",
      "type": "object",
      "oneOf": [

        { "$ref": "#/definitions/os_properties" },
        { "$ref": "#/definitions/db_properties" },
        { "$ref": "#/definitions/api_properties" }

      ]
    }
  },
  "required": [ "name", "run" ],
  "additionalProperties":  false
}
)";

string test_json = R"(
{
    "name": "testing flow", 
    "run" : {
            "command": "some command"    
            }
}

)";


int main() {


    try
    {
        json schema = json::parse(test_schema);
        json data = json::parse(test_json);
        // Will throw schema_error if JSON Schema loading fails
        auto sch = jsonschema::make_schema(schema);

        std::size_t error_count = 0;
        auto reporter = [&error_count](const jsonschema::validation_output& o)
        {
            ++error_count;
            std::cout << o.instance_location() << ": " << o.message() << "\n";
        };

        jsonschema::json_validator<json> validator(sch);

        // Will call reporter for each schema violation
        json patch = validator.validate(data, reporter);

        //jsonpatch::apply_patch(patch, data);
        std::cout << "\nError count: " << error_count << "\n\n";

        const job_properties v = jsoncons::decode_json<job_properties>(test_json);
        string en;
        jsoncons::encode_json_pretty(v, en);
        cout << "Given json is: " << en << endl;

    }
    catch (const std::exception& e)
    {
        std::cout << e.what() << '\n';
    }



    return 0;
}

OUTPUT

Error count: 0

Given json is: {
    "name": "testing flow",
    "run": {}
}

In the above output, "run" object is empty, but we passed "command" property.
I am using the Visual Studio Community 2019 version, and below is the compiler version

C:\Program Files (x86)\Microsoft Visual Studio\2019\Community>cl
Microsoft (R) C/C++ Optimizing Compiler Version 19.27.29111 for x64

danielaparker · 2020-12-31T05:20:53Z

danielaparker
Dec 31, 2020
Maintainer

If you can use C++17, and <variant>, I would suggest doing it this way:

#include <jsoncons/json.hpp>
#include <jsoncons_ext/jsonpath/jsonpath.hpp>
#include <jsoncons_ext/jsonschema/jsonschema.hpp>
#include <jsoncons_ext/jsonpatch/jsonpatch.hpp>
#include <iostream>
#include <string>
#include <fstream>
#include <variant>

using json = jsoncons::json;
namespace jsonschema = jsoncons::jsonschema;
namespace jsonpatch = jsoncons::jsonpatch;

struct os_properties {
    std::string command;
};

struct db_properties {
    std::string query;
};

struct api_properties {
    std::string target;
};

struct job_properties {
    std::string name;
    std::variant<os_properties,db_properties,api_properties> run;
};

JSONCONS_N_MEMBER_TRAITS(os_properties, 1, command)
JSONCONS_N_MEMBER_TRAITS(db_properties, 1, query)
JSONCONS_N_MEMBER_TRAITS(api_properties, 1, target)
JSONCONS_N_MEMBER_TRAITS(job_properties, 2, name, run)

std::string test_schema = R"(
{
  "title": "job",
  "description": "job properties json schema",
  "definitions": {
    "os_properties": {
      "type": "object",
      "properties": {
        "command": {
          "description": "this is the OS command to run",
          "type": "string",
          "minLength": 1
        }
      },
      "required": [ "command" ],
      "additionalProperties": false
    },
    "db_properties": {
      "type": "object",
      "properties": {
        "query": {
          "description": "this is db query to run",
          "type": "string",
          "minLength": 1
        }
      },
      "required": [ "query" ],
      "additionalProperties": false
    },

    "api_properties": {
      "type": "object",
      "properties": {
        "target": {
          "description": "this is api target to run",
          "type": "string",
          "minLength": 1
        }
      },
      "required": [ "target" ],
      "additionalProperties": false
    }
  },

  "type": "object",
  "properties": {
    "name": {
      "description": "name of the flow",
      "type": "string",
      "minLength": 1
    },
    "run": {
      "description": "job run properties",
      "type": "object",
      "oneOf": [

        { "$ref": "#/definitions/os_properties" },
        { "$ref": "#/definitions/db_properties" },
        { "$ref": "#/definitions/api_properties" }

      ]
    }
  },
  "required": [ "name", "run" ],
  "additionalProperties":  false
}
)";

std::string test_json = R"(
{
    "name": "testing flow", 
    "run" : {
            "command": "some command"    
            }
}

)";


int main() {


    try
    {
        json schema = json::parse(test_schema);
        json data = json::parse(test_json);
        // Will throw schema_error if JSON Schema loading fails
        auto sch = jsonschema::make_schema(schema);

        std::size_t error_count = 0;
        auto reporter = [&error_count](const jsonschema::validation_output& o)
        {
            ++error_count;
            std::cout << o.instance_location() << ": " << o.message() << "\n";
        };

        jsonschema::json_validator<json> validator(sch);

        // Will call reporter for each schema violation
        json patch = validator.validate(data, reporter);

        //jsonpatch::apply_patch(patch, data);
        std::cout << "\nError count: " << error_count << "\n\n";

        //const job_properties v = jsoncons::decode_json<job_properties>(test_json); 
        const job_properties v = data.as<job_properties>(); // You don't need to reparse test_json 

        std::string en;
        jsoncons::encode_json_pretty(v, en);
        std::cout << "Given json is: " << en << std::endl;

        // Test that it validates
        json test = json::parse(en);
        validator.validate(test, reporter);
        std::cout << "\nError count: " << error_count << "\n\n";
    }
    catch (const std::exception& e)
    {
        std::cout << e.what() << '\n';
    }

    return 0;
}

Output:

Error count: 0

Given json is: {
    "name": "testing flow",
    "run": {
        "command": "some command"
    }
}

Error count: 0

0 replies

dineshkumar02 · 2020-12-31T15:51:57Z

dineshkumar02
Dec 31, 2020
Author

@danielaparker Thank you very much for your help.

I have been targeting the code with C++11 and will take your suggestions If I switch to C++17.

0 replies

danielaparker · 2020-12-31T16:24:26Z

danielaparker
Dec 31, 2020
Maintainer

With C++11, you can use

struct run_properties {
    jsoncons::optional<std::string> command;
    jsoncons::optional<std::string> query;
    jsoncons::optional<std::string> target;
};

struct job_properties {
    std::string name;
    run_properties run;
};

JSONCONS_N_MEMBER_TRAITS(run_properties, 0, command, query, target)
JSONCONS_N_MEMBER_TRAITS(job_properties, 2, name, run)

But that corresponds more to "anyOf" than "oneOf".

0 replies

Provide feedback

Saved searches

Use saved searches to filter your results more quickly

JSON schema & decode object #300

{{title}}

{{editor}}'s edit

{{editor}}'s edit

Replies: 4 comments 1 reply

{{title}}

{{editor}}'s edit

{{editor}}'s edit

{{title}}

{{title}}

{{editor}}'s edit

{{editor}}'s edit

{{title}}

{{title}}

Select a reply

JSON schema & decode object #300

dineshkumar02 Dec 30, 2020

Replies: 4 comments · 1 reply

danielaparker Dec 30, 2020 Maintainer

dineshkumar02 Dec 31, 2020 Author

danielaparker Dec 31, 2020 Maintainer

dineshkumar02 Dec 31, 2020 Author

danielaparker Dec 31, 2020 Maintainer

dineshkumar02
Dec 30, 2020

Replies: 4 comments 1 reply

danielaparker
Dec 30, 2020
Maintainer

dineshkumar02 Dec 31, 2020
Author

danielaparker
Dec 31, 2020
Maintainer

dineshkumar02
Dec 31, 2020
Author

danielaparker
Dec 31, 2020
Maintainer